The field of the invention is generally directed to remote geolocation finding without using a magnetic based North seeking system as well as error determination of accuracy of the remote geolocation determinations.
Embodiments of the invention address a need for remote geolocation and error determination based on an ability to quickly find an accurate heading of a hand carried device without the need for magnetic field measurement. Portable systems capable of being carried by humans in a typical application desired by persons moving across country based on non-magnetic north (or south) seeking systems are not available due to a variety of limiting factors including size, weight, and power. Accordingly, in simplified terms, an invention has been created to provide a needed capability to determine a desired orientation of a sensor at a desired point with respect to the Earth (e.g., true north) based on determination of orientation of a reference axis of a sensor with respect to locations of multiple points and relationships between the multiple points with a significant degree of accuracy using non-magnetic directional sensing, orientation sensing, determinations via global positioning satellites (GPS), and a sequence of measurements along a displaced path which are used to align a virtual inertial navigation unit (INU) having three axis based on orientation sensor systems placed in a strap down configuration and aligned with a laser rangefinder used to determine range to a desired target location. Location can include elevation of the sensor at each point of measurement which can be used in an embodiment. A desired orientation of the sensor at a desired point can include the first point at which a suitably accurate orientation, e.g., true north, can be determined e.g., less than five mil degrees accuracy (e.g., an angular mill can be found by dividing 360 degrees by 6000). A sequence of measurements can include at least two measurements in accordance with an embodiment of the invention along a path of travel which is, for example, not purely vertical in elevation.
An embodiment of the non-magnetic directional sensing, navigational and orientation system can include an inertial navigation system coupled with a GPS system along with a control system adapted for executing a series of computations and generating results in accordance with an embodiment of the invention. Accordingly, multiple measurements and determinations can be made until a predetermined orientation accuracy value has been found to be achieved.
For example, an embodiment can provide a solution to meet unmet needs that include, for simplification purposes, two parts. A first general part includes deriving a series of accurate location, elevation, and heading determinations via GPS. A second part includes accurately capturing an orientation of a sensing device in accordance with an embodiment of the invention and thus a direction that the non-magnetic sensor is pointing or orientated. An embodiment of the invention also includes a system adapted to execute the above parts in a variety of sequences to determine required information that is in turn used to identify with significant precision a needed geodetic or Earth fixed orientation.
An additional embodiment also is adapted to remote sensing of a specific location of an object of interest/location based on a combination of current navigation location/orientation and remote sensing of distance/orientation to the location/object of interest. For example, an embodiment of the invention can provide a remote sensing/determination of position of an object/location of interest based on the non-magnetic based location/navigation/orientation determination capability. An example of remote sensing embodiments can include addition of a laser range finder in addition to an additional set of computations in a control system in accordance with an embodiment of the invention. An exemplary embodiment can determine remote coordinates of an object of interest/location using such an embodiment.
Generally, an embodiment can include a remote geolocation system and related methods including an INU having orthogonally disposed three axis accelerometers/gyroscopes in a strap down configuration in a case, a laser range finder (LRF) aligned with one INU axis, a GPS, and machine instructions that create a virtual INU (VINU) used to determine orientation of the case at an activation point (AP) when the LRF is pointed at a target, take sequences of GPS location data and inertial measuring unit (IMU) orientation measurements from a starting location to the AP, draw a line between the starting location and the AP, identify a longitude line (LL) passing through the line, aligns one VINU axis with the LL, aligns another VINU axis with INU detected gravity, and aligns a remaining VINU axis with the LRF's output at the AP. The aligned VINU, GPS, and LRF are used to determine latitude, longitude, elevation, and position error of the target. Various methods are also provided.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.